Coal is the single largest commodity by volume that is transported by the North American railroads. Typically, the utility companies implement multiple unit trains consisting of approximately 100 (or more) open-top hopper cars that continuously run from the mines to the power plants to provide a continuous supply of coal. In fact, the railroads are the most efficient and cost effective means to haul the coal. However, the utility companies, and other coal purchases, are constantly looking for ways to increase their productivity and lower their costs by hauling more coal per unit train. Utility companies, and others, have been able to accomplish this by, among other things, adding additional cars to the unit train, increasing the gross rail load per car permitted by the Association of American Railroads (“AAR”), and by converting the open-top hopper cars from steel to aluminum.
Unfortunately, despite these efforts, it has been discovered that there is an increasing amount of coal being lost as it is transported from the mines to the power plants. A portion of this loss is due to spillage at the loading and unloading facilities and/or by aerodynamic effects as the car travels down the tracks at speeds of up to 70 mph. Typically, the level of the loaded coal will be above the top of the open-top hopper car and, thus, some coal particles will be blown off as the car travels down the tracks. However, a fairly substantial portion of the loss is a result of gaps that exist in the railroad car structure itself. One such gap typically exists between the sidewall and trough (floor) of the hopper car, which gap can be as large as ½″ or more and can result in a loss of approximately 200 to 500 pounds of coal per car per trip, depending, of course, on the size of the gap and the size of the coal loaded into the car. Beyond the obvious loss of revenue and efficiencies, this has also resulted in the degradation of the track ties and substructure, as the sulfur in the spilled coal combines with rain water to create sulfuric acid, which eats away at the track ties and substrate.
Previous attempts to fix or close these gaps have not met with much success. One attempted method has been to apply caulk to fill the gaps. However, the caulk is generally not strong enough to form a good seal, especially where the gap is appreciable. Since the railroad cars have, for the most part, been converted to aluminum, welding is therefore an issue and is thus not a preferred means of sealing any gaps.
Any seal will also need to withstand the forces and pressures associated with the loading and unloading of coal or other minerals into and out of the railroad car. Additionally, the seal needs to be resistant to sulfuric acid to prevent the seal from deteriorating over time, especially if the seal is used in a railroad car that transports primarily coal.
The present invention is directed toward overcoming one or more of the above-identified problems.